CN117801186A - Polymer, negative electrode plate and battery - Google Patents

Polymer, negative electrode plate and battery Download PDF

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Publication number
CN117801186A
CN117801186A CN202311857387.8A CN202311857387A CN117801186A CN 117801186 A CN117801186 A CN 117801186A CN 202311857387 A CN202311857387 A CN 202311857387A CN 117801186 A CN117801186 A CN 117801186A
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polymer
negative electrode
structural unit
repeating structural
alkyl
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潘珊珊
刘春洋
李素丽
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Zhuhai Cosmx Battery Co Ltd
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Zhuhai Cosmx Battery Co Ltd
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/62Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624Electric conductive fillers
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08FMACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F293/00Macromolecular compounds obtained by polymerisation on to a macromolecule having groups capable of inducing the formation of new polymer chains bound exclusively at one or both ends of the starting macromolecule
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/05Accumulators with non-aqueous electrolyte
    • H01M10/052Li-accumulators
    • H01M10/0525Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/13Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/62Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/628Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10Energy storage using batteries

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

The invention relates to the technical field of batteries, in particular to a polymer, a negative electrode plate and a battery. The polymer comprises a repeating structural unit A shown in a formula (I) and a repeating structural unit B shown in a formula (II), wherein R 1 comprises-NR 5 R 6 、‑ONR 5 R 6 、‑CONR 5 R 6 、‑COO(CH 2 ) a NR 5 R 6 ,R 5 And R is 6 Each independently selected from at least one of-H, -OH, C1-C12 alkyl or C6-C18 aryl, a is an integer from 0 to 10; r is R 3 At least one of an alkyl group comprising C1-C12 or an acid ester thereof, or an aryl group comprising C6-C18 or an acid ester thereof; r is R 2 And R is 4 Each independently ofThe ground includes H or C1-C3 alkyl. The polymer has hydrophilicity and hydrophobicity, and the negative plate containing the polymer can improve the transmission speed of lithium ions and electrons and improve the quick charge performance and the rate capability of the battery.

Description

Polymer, negative electrode plate and battery
Technical Field
The invention relates to the technical field of batteries, in particular to a polymer, a negative electrode plate comprising the polymer and a battery comprising the negative electrode plate.
Background
The lithium ion battery is a high-new technology product, and is a novel high-capacity long-life environment-friendly battery, and the lithium ion battery consists of a positive electrode, a negative electrode and electrolyte, is excellent in product performance, and is mainly used in various fields such as mobile phones, notebooks, electric automobiles and electric toys. Compared with nickel-cadmium and nickel-hydrogen batteries, the lithium ion battery has the advantages of high voltage, large specific energy, long cycle life, good safety performance, small self-discharge, no memory effect, quick charge and discharge, wide working temperature range and the like.
However, in the practical application process of the lithium ion battery, there is a risk of lithium precipitation, and lithium precipitation is often caused by slow transmission and combination of lithium ions and electrons, so that lithium dendrites are formed on the surface of the pole piece.
Therefore, the invention is very important to avoid the risk of lithium precipitation, and has good quick charge performance, good rate capability and prolonged service life.
Disclosure of Invention
The present invention has been made to overcome the above-mentioned problems occurring in the prior art, and an object of the present invention is to provide a polymer, a negative electrode tab including the polymer, and a battery including the negative electrode tab. The polymer of the invention comprises anions and cations, and has hydrophilicity and hydrophobicity; the negative plate obtained by the polymer can accelerate the combination of lithium ions and electrons and improve the transmission speed of the lithium ions and the electrons; the battery obtained by the negative plate can improve the quick charge performance, the multiplying power performance and the capacity retention rate of the battery.
The inventor of the invention discovers that by improving the transmission speed of lithium ions and electrons, the risk of lithium precipitation can be avoided, the quick charge performance and the rate capability of the battery are improved, and the service life of the battery is prolonged.
The inventor of the invention further researches and discovers that in order to improve the transmission speed of lithium ions and electrons, substances with specific structures can be added into the negative electrode plate, and the substances contain hydrophilic and hydrophobic groups, so that the transmission speed of the lithium ions and electrons is accelerated, and the system dynamics is further improved, thereby improving the lithium precipitation condition, improving the quick charge performance and the multiplying power performance of the battery and prolonging the service life of the battery.
In order to achieve the above object, the first aspect of the present invention provides a polymer which is a block copolymer comprising a repeating structural unit A represented by the formula (I) and a repeating structural unit B represented by the formula (II),
wherein R is 1 Comprises- (CH) 2 ) a NR 5 R 6 、-O(CH 2 ) a NR 5 R 6 、-CO(CH 2 ) a NR 5 R 6 、-COO(CH 2 ) a NR 5 R 6 ,R 5 And R is 6 Each independently selected from at least one of-H, -OH, C1-C12 alkyl or C6-C18 aryl, a is an integer from 0 to 10;
R 3 at least one of an alkyl group comprising C1-C12 or an acid ester thereof, or an aryl group comprising C6-C18 or an acid ester thereof;
R 2 and R is 4 Each independently includes H or C1-C3 alkyl.
The second aspect of the present invention provides a negative electrode sheet comprising a negative electrode current collector and a negative electrode active material layer located on one side or both sides of the negative electrode current collector, the negative electrode active material layer comprising a negative electrode active material, a conductive agent, and the polymer according to the first aspect of the present invention.
A third aspect of the invention provides a battery comprising a polymer according to the first aspect of the invention, and/or a negative electrode sheet according to the second aspect of the invention.
Through the technical scheme, compared with the prior art, the invention has at least the following advantages:
the polymer has hydrophilicity and hydrophobicity, and the negative plate prepared by using the polymer can accelerate the combination of lithium ions and electrons and improve the transmission speed of the lithium ions and the electrons; and the prepared battery can avoid lithium precipitation risk, improve quick charge performance and rate capability and prolong service life.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein. Herein, unless otherwise specified, data ranges all include endpoints.
Drawings
FIG. 1 is a schematic view of a polymer according to the present invention.
FIG. 2 is a graph showing the cycle performance test of the examples and comparative examples of the present invention.
Fig. 3 is a graph showing low-temperature discharge performance test of the examples and comparative examples of the present invention.
Fig. 4 shows the rate performance test charts of the examples and comparative examples of the present invention.
Detailed Description
The following describes specific embodiments of the present invention in detail. It should be understood that the detailed description and specific examples, while indicating and illustrating the invention, are not intended to limit the invention.
Unless defined otherwise, all scientific and technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention relates.
The first aspect of the present invention provides a polymer which is a block copolymer comprising a repeating structural unit A represented by the formula (I) and a repeating structural unit B represented by the formula (II),
wherein R is 1 Comprises- (CH) 2 ) a NR 5 R 6 、-O(CH 2 ) a NR 5 R 6 、-CO(CH 2 ) a NR 5 R 6 、-COO(CH 2 ) a NR 5 R 6 ,R 5 And R is 6 Each independently selected from at least one of-H, -OH, C1-C12 alkyl or C6-C18 aryl, a is an integer from 0 to 10;
R 3 at least one of an alkyl group comprising C1-C12 or an acid ester thereof, or an aryl group comprising C6-C18 or an acid ester thereof;
R 2 and R is 4 Each independently includes H or C1-C3 alkyl.
In some embodiments, the content of the repeating structural unit a is 10-90wt%, based on the total weight of the polymer, and may be, for example, 10, 20, 30, 40, 50, 60, 70, 80, 90wt%, or any range between any two values; the content of the repeating structural unit B is 10 to 90wt%, and may be, for example, 10, 20, 30, 40, 50, 60, 70, 80, 95wt% or any range between any two values. Preferably, the content of the repeating structural unit A is 30 to 70wt% and the content of the repeating structural unit B is 30 to 70wt% based on the total weight of the polymer.
In some embodiments, R 1 Comprises- (CH) 2 ) a NR 5 R 6 、-O(CH 2 ) a NR 5 R 6 、-CO(CH 2 ) a NR 5 R 6 、-COO(CH 2 ) a NR 5 R 6 ,R 5 And R is 6 Each independently selected from at least one of-H, -OH, C1-C6 alkyl or C6-C12 aryl, and a is an integer of 0 to 5. For example, R 5 、R 6 Each independently selected from at least one of-H, -OH, methyl, ethyl, propyl, phenyl, and tolyl.
In some embodiments, R 3 Comprising C1-C6 alkyl or acid ester thereof, or C6-C10 aryl or acid ester thereof, preferably R 3 Comprising a armorAt least one of a group, an ethyl group, an isopropyl group, an n-butyl group, a tolyl group, and a sulfonic group. Preferably, the acid ester group is selected from the group consisting of-SO 3 - 、-P(OH) 3 、CrO 4 2- 、Cr 2 O 7 2- And NO 3- At least one of them.
In some embodiments, R 2 And R is 4 Each independently is H or methyl.
Further preferably R 1 -R 4 The range of the substituent groups can enable the polymer to better exert hydrophilicity and hydrophobicity, improve the combination speed of lithium ions and electrons, and improve the quick charge performance and the rate capability of the battery.
In some implementations, the polymer includes n hydrophilic units a and m hydrophobic units B, wherein R in each of the hydrophilic units 1 R in each of the hydrophobic units B may be the same or different 2 May be the same or different.
In some embodiments, the repeating structural unit a and the repeating structural unit B are linked by a c—c bond, and the molecular formula (V) of the polymer is as follows:
R 1 comprises- (CH) 2 ) a NR 5 R 6 、-O(CH 2 ) a NR 5 R 6 、-CO(CH 2 ) a NR 5 R 6 、-COO(CH 2 ) a NR 5 R 6 ,R 5 And R is 6 Each independently selected from at least one of-H, -OH, C1-C12 alkyl or C6-C18 aryl, a is an integer from 0 to 10; r is R 3 At least one of an alkyl group comprising C1-C12 or an acid ester thereof, or an aryl group comprising C6-C18 or an acid ester thereof; r is R 2 And R is 4 Each independently includes H or C1-C3 alkyl.
In some embodiments, m may be any integer in the range of 100-10000, for example, may be 100, 500, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000.
In some embodiments, m is any integer in the range of 200-500.
In some embodiments, n may be any integer in the range of 100-10000, for example, 100, 500, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000.
In some embodiments, n is any integer in the range of 200-500.
When the values of m and n are in the above range, the number of hydrophilic units A and hydrophobic units B can be controlled, so that the polymer can better exert hydrophilicity and hydrophobicity in the aqueous solvent and the organic solvent, the combination speed of lithium ions and electrons is improved, and the quick charge performance and the rate capability of the battery are improved.
In some embodiments, the polymer has a structure represented by formula (IV):
wherein m is any integer in the range of 100-10000, and n is any integer in the range of 100-10000. The polymer shown in the formula (IV) contains hydrophilic N-containing groups (such as amino, amide, polyimide and the like) and a structure containing hydrophobic acid ester groups, so that the lithium ion and electron conduction speed can be further accelerated, the system dynamics can be improved, and the quick charge capacity of a battery containing the polymer can be improved.
Since the polymer comprises one or more hydrophilic units a and one or more hydrophobic units B, the polymer has both hydrophilicity and hydrophobicity and is thus capable of functioning in both aqueous and organic solvents. The polymer has a core-shell structure, as shown in fig. 1, with a hydrophobic shell and a hydrophilic core (or a hydrophilic shell and a hydrophobic core). And the polymer has anions and cations, so the polymer is capable of transporting lithium ions and electrons.
Preferably, the hydrophilic repeating structural unit a is a shell and the hydrophobic repeating structural unit B is a core. When the polymer is applied to preparing the anode active slurry, the polymer is better dissolved and dispersed in a water system of the anode active slurry, so that the anode plate can accelerate the combination of lithium ions and electrons.
In some embodiments, the weight ratio of the hydrophilic units a to the hydrophobic units B in the polymer is 1 (0.1-9) (e.g., 1:0.1, 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:5, 1:7, 1:9). By adjusting the weight ratio of the hydrophilic unit to the hydrophobic unit B within a certain range, the polymer can be made to exert hydrophilicity and hydrophobicity better in an aqueous solvent and an organic solvent.
In some embodiments, the weight ratio of the hydrophilic units A to the hydrophobic units B in the polymer is 1 (1-3).
In some embodiments, the repeating structural unit a comprises a first monomer having a structure of formula (ii), and the repeating structural unit B comprises a second monomer having a structure of formula (IV);
wherein R is 1 Comprises- (CH) 2 ) a NR 5 R 6 、-O(CH 2 ) a NR 5 R 6 、-CO(CH 2 ) a NR 5 R 6 、-COO(CH 2 ) a NR 5 R 6 ,R 5 And R is 6 Each independently selected from at least one of-H, -OH, C1-C12 alkyl or C6-C18 aryl, a is an integer from 0 to 10;
R 2 at least one of an alkyl group comprising C1-C12 or an acid ester thereof, or an aryl group comprising C6-C18 or an acid ester thereof;
R 2 and R is 4 Each independently includes H or C1-C3 alkyl.
The hydrophilic unit a in the polymer may be prepared by homo-and/or co-polymerization of the first monomer. The hydrophilic unit comprises a 1 -a 1 And/or a 1 -a 2 Block structure of (2)Constructing a structure. The hydrophobic unit B in the polymer may be prepared by homo-and/or co-polymerization of the second monomer. The hydrophobic unit B comprises a block structure of B1-B1 and/or B1-B2.
In some embodiments, the first monomer comprises N, N-dimethylaminoethyl methacrylate and/or N, N-dimethylacrylamide.
In some embodiments, the second monomer comprises one or more of methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, butyl methacrylate, benzyl methacrylate, sulfonate methacrylate.
In some embodiments, the number average molecular weight of the polymer is 10000-1000000g/mol (e.g., 10000g/mol, 20000g/mol, 30000g/mol, 40000g/mol, 50000g/mol, 100000g/mol, 500000g/mol, 1000000 g/mol).
In some embodiments, the number average molecular weight of the polymer is 10000g/mol to 50000g/mol, e.g., 10000g/mol, 20000g/mol, 30000g/mol, 40000g/mol, 50000g/mol. When the number average molecular weight of the polymer is in the range, a core-shell structure is formed in an organic system or an aqueous system more easily, the core-shell structure is more stable, the electron and lithium ion conduction is further accelerated, the quick charge performance and the rate capability of the battery are improved, and the service life of the battery is prolonged.
The invention also provides a preparation method of the polymer in the first aspect, which comprises the following steps:
in the presence of an initiator, carrying out first polymerization on a first monomer in water to obtain a product after a first polymer, and then adding a second monomer into the product after the first polymerization and carrying out second polymerization to obtain the polymer;
wherein the first monomer has a structure shown in a formula (III), and the second monomer has a structure shown in a formula (IV);
wherein R is 1 Comprises- (CH) 2 ) a NR 5 R 6 、-O(CH 2 ) a NR 5 R 6 、-CO(CH 2 ) a NR 5 R 6 、-COO(CH 2 ) a NR 5 R 6 ,R 5 And R is 6 Each independently selected from at least one of-H, -OH, C1-C12 alkyl or C6-C18 aryl, a is an integer from 0 to 10;
R 3 selected from C1-C12 alkyl or its acid ester, or C6-C18 aryl or its acid ester, and the acid ester group is selected from-SO 3 - 、-P(OH) 3 、CrO 4 2- 、Cr 2 O 7 2- And NO 3- At least one of (a) and (b);
R 2 and R is 4 Each independently selected from H or C1-C3 alkyl;
wherein the amount of the first monomer is 5-95wt% and the amount of the second monomer is 5-95wt% based on the total weight of the monomers.
In one example, the first polymerization conditions include: the temperature is 60-90 ℃ and the time is 0.5-3h.
In one example, the second polymerization conditions include: the temperature is 80-100deg.C, and the time is 0.5-3h.
In some embodiments, the initiator is selected from one or more of azo compounds, peroxides, and complex initiators.
In some embodiments, the azo compound includes Azobisisobutyronitrile (AIBN), azobisisoheptonitrile (ABVN), azobisisobutyrimidine hydrochloride (AIBA), azobisiso Ding Mi-in hydrochloride (AIBI), and azobisisob Ding Qingji-carboxamide (V30), and the like.
In some embodiments, the peroxide comprises benzoyl peroxide, t-butyl benzoyl peroxide, methyl ethyl ketone peroxide, and the like.
In some embodiments, the composite initiator may include at least two azo compound initiators, or at least two peroxide initiators, or a combination of at least one azo compound initiator and at least one peroxide initiator.
In some embodiments, the stirring is performed at a speed of 30-100 rpm/s.
In some embodiments, the latex solution has a solids content of 35wt% to 40wt%.
The polymer may be used alone or in combination with other binders, which may be conventional in the art, such as one or more of Styrene Butadiene Rubber (SBR) and acrylate polymers.
The invention also provides application of the polymer in the field of batteries. The polymer can be used as a binder, can be matched with other binders for use, and can also be used independently.
The second aspect of the present invention provides a negative electrode sheet comprising a negative electrode current collector and a negative electrode active material layer located on one side or both sides of the negative electrode current collector, the negative electrode active material layer comprising a negative electrode active material, a conductive agent, and the polymer according to the first aspect of the present invention.
The binder in the negative electrode sheet mainly plays a role in increasing the adhesion between the negative electrode active materials and the negative electrode current collector, and cannot play a role in the transmission of lithium ions between the negative electrode sheet layers (namely between the negative electrode current collector and the negative electrode active material layer). The negative electrode sheet uses water as a solvent, and does not promote the transfer of lithium ions and electrons when the negative electrode sheet is contacted with an electrolyte based on an organic solvent.
The polymer comprises anions and cations, has hydrophilicity and hydrophobicity, and can improve the transmission speed of lithium ions and electrons under the infiltration of electrolyte organic solvent, so that the dynamic performance of a system is improved, and the lithium separation risk is avoided.
In some embodiments, the anode active material layer further includes a halogen-containing ester. The halogen-containing esters may be the hydrolyzable esters commonly used in the art containing fluorine (F), chlorine (Cl), bromine (Br), iodine (I), preferably the hydrolyzable esters containing chlorine.
In some embodiments, the halogen-containing esters include ethyl chloroacetate and/or methyl chloroacetate.
After the amphiphilic ionic polymer is dissolved in an aqueous solvent, adding a hydrolyzable ester containing halogen, wherein the halogen ion can react with an N-containing group (such as amino, amide, polyimide and the like) in the photopolymer to form N+ cations, so as to form an anion-cation pair, accelerate the conduction speed of lithium ions and electrons, and further improve the quick charge performance of the battery.
In some embodiments, the mass ratio of the polymer to the hydrolyzable ester is 1 (0.5-1.5). Preferably, the mass ratio of the polymer to the halogen-containing hydrolyzable esters promotes more anion-cation pairs formed by the reaction of the N-containing groups in the polymer with the hydrolyzable esters, further accelerating lithium ion and electron conduction rates.
The materials and the preparation method of the negative plate except the polymer can be carried out according to the mode in the field, and the effects of accelerating the combination of lithium ions and electrons and improving the transmission speed of the lithium ions and the electrons can be achieved.
The negative electrode current collector may be a negative electrode current collector conventional in the art, for example, the negative electrode current collector is a copper foil.
The anode active material may be an anode active material conventional in the art, for example, the anode active material includes artificial graphite, natural graphite, soft carbon, hard carbon, or an anode active material containing 1 to 20wt% SiO x At least one of/C or Si/C graphite composite material, wherein 0<x<2。
The conductive agent may be a conductive agent conventional in the art, for example, the conductive agent includes one or more of conductive carbon black (SP), acetylene black, ketjen black, graphene, conductive carbon fiber, 350G, carbon Nanotubes (CNTs), metal powder, and carbon fiber.
In some embodiments, the weight content of the polymer is 0.5 to 3wt% (e.g., 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3 wt%) based on the total weight of the anode active material layer.
In some embodiments, the weight content of the anode active material is 92-97wt% (e.g., 92wt%, 93wt%, 94wt%, 95wt%, 96wt%, 97 wt%) and the weight content of the conductive agent is 0.1-2wt% (e.g., 0.1wt%, 0.3wt%, 0.5wt%, 0.8wt%, 1wt%, 1.5wt%, 2 wt%), based on the total weight of the anode active material layer.
In some embodiments, the polymer is present in an amount of 1 to 1.5wt%, the negative electrode active material is present in an amount of 97 to 99wt%, and the conductive agent is present in an amount of 0.5 to 1wt%, based on the total weight of the negative electrode active material layer.
In some embodiments, the anode active material layer further includes a binder. Besides the polymer, the binder is added, so that the binding force between the anode active material layer and the current collector can be further improved, and the stability of the anode is improved.
The binder may be a binder conventional in the art, for example, the binder is selected from one or more of styrene-butadiene rubber, PAA polymer and block polymer.
In some embodiments, the binder includes one or more of Styrene Butadiene Rubber (SBR), sodium carboxymethyl cellulose, styrene Butadiene Rubber (SBR), polytetrafluoroethylene, polyethylene oxide, and acrylate polymers.
In some embodiments, the weight content of the binder is 0-3wt% (e.g., 0wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3 wt%) based on the total weight of the anode active material layer.
In some embodiments, the binder is present in an amount of 0.5 to 1.5wt% based on the total weight of the anode active material layer.
In some embodiments, the negative electrode active material layer further includes a thickener. The thickener comprises sodium carboxymethyl cellulose (CMC), and one or two of sodium carboxymethyl cellulose.
The polymer provided by the invention is contained in the negative plate, so that the combination of lithium ions and electrons in the negative plate is improved, and the transmission speed of the lithium ions and electrons is improved.
A third aspect of the invention provides a battery comprising a polymer according to the first aspect of the invention, and/or a negative electrode sheet according to the second aspect of the invention.
The materials and the preparation method of the battery except the negative electrode plate can be carried out according to the mode in the field, and the effects of avoiding the problem of lithium precipitation, along with good quick charge performance, good multiplying power performance and long service life can be achieved.
The battery provided by the invention has the advantages that the battery can avoid the problem of lithium precipitation, the quick charge performance is improved, the multiplying power performance is improved, and the service life is prolonged due to the negative plate.
The technical solutions in the embodiments of the present invention will be clearly and completely described in the following in conjunction with the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Materials, reagents and the like used in the examples described below are commercially available unless otherwise specified.
The invention is described in detail below in connection with specific embodiments, which are intended to be illustrative rather than limiting.
The following examples illustrate the polymers and negative electrode sheets of the present invention.
Example 1
(1) Preparation of the Polymer
Adding an initiator azodiisobutyronitrile and a first monomer N, N-dimethylaminoethyl methacrylate into a sealed and dried wide-mouth bottle to prepare a hydrophilic repeating structural unit A, adding a second monomer methyl methacrylate into the wide-mouth bottle to prepare an amphiphilic ionic block polymer, adding the polymer into water, and stirring at a speed of 100rpm/s to form a core-shell structure latex solution (the hydrophilic unit is a shell and the hydrophobic unit is a core), wherein the solid content of the latex solution is 40%, and the mass ratio of the first monomer to the second monomer is 1:1.
(3) Preparation of negative electrode sheet
Adding negative electrode active material graphite, conductive agent graphite, thickener CMC and polymer into a planetary stirring tank, wherein the mass ratio of the active materials is 97 percent: 0.5%:1.2%:1.3 percent of water is taken as a solvent, the mixture is stirred at the rotation speed of 500r/min and revolution speed of 2000r/min to prepare anode active material slurry, the anode active material slurry is coated on an anode current collector copper foil, and the anode active material slurry is dried in a 90-degree oven to prepare the fast-charge anode plate.
Example 2
The procedure of example 1 was followed, except that the mass ratio of the first monomer to the second monomer was 3:7.
Example 3
The procedure of example 1 was followed, except that the mass ratio of the first monomer to the second monomer was 1:9.
Example 4
The procedure of example 1 was followed, except that 4wt% ethyl chloroacetate was further added to the core-shell latex solution.
Example 5
The procedure of example 1 was followed, except that 2wt% of methyl chloroacetate was further added to the core-shell latex solution.
Comparative example 1
Reference example 1 was performed, except that the polymer was replaced with an equal amount of SBR.
Preparation example
The negative electrode sheets obtained in examples and comparative examples were each prepared as follows. .
(1) Preparation of positive plate
And (3) stirring lithium cobaltate, a conductive agent and PVDF in an NMP solvent according to a mass ratio of 97:2:1 at a rotating speed of 800 revolutions and 2500 revolutions/min to prepare positive electrode slurry, coating the slurry on 10-micrometer aluminum foil, and drying in a 120-degree oven to prepare the positive electrode plate.
(2) Preparation of negative plate
The negative electrode sheets obtained in the above examples and comparative examples were used, respectively.
(3) Electrolyte preparation
LiPF with electrolyte of 1mol/L 6 And EC, DMC mixed solution.
(4) Preparation of a Battery
The positive and negative plates are arranged on two sides of the diaphragm and wound into a winding core, and then the battery is manufactured through the steps of packaging, liquid injection, formation, secondary sealing, capacity division and the like.
Test case
The batteries obtained in examples and comparative examples were each subjected to the following test:
(1) Normal temperature cycle test
The battery was charged at a 3C rate and discharged at a 1C rate using a charge-discharge apparatus at normal temperature of 25 ℃, and in this way, the battery was cycled for 1000T with a capacity ratio=cap.x/cap.3×100%, i.e., the ratio of the discharge capacity of cycle X to the discharge capacity of cycle third, the result of which is shown in fig. 2.
(2) Low temperature discharge performance
The battery was charged at 0.5C rate using a charge-discharge device, and discharged at different temperatures by 0.2C rate, with a capacity ratio=cap.x/cap.rt of 100%, i.e., a ratio of the discharge capacity of the cycle X to the discharge capacity at normal temperature, and the result is shown in fig. 3.
(3) Multiplying power charging performance test
The battery was charged at different rates using a charge-discharge apparatus, and was discharged at 0.2C rate, with a capacity ratio=cap.x/cap (0.5C) of 100%, i.e., a ratio of discharge capacity at cycle X to discharge capacity at 0.5C, and the result is shown in fig. 4.
The results of the normal temperature cycle test of the batteries provided in examples 1 to 3 and comparative example 1 are shown in fig. 2, and the capacity retention rate is still higher than 90% when the battery of example 1 is cycled for 500 cycles; the capacity retention rate was still higher than 90% for 300 cycles of the battery of example 2, and higher than 85% for 200 cycles of the battery of example 3. While the battery of comparative example 1 had a capacity retention of less than 90% at around 150 cycles. Therefore, in the embodiment of the invention, the polymer shown in the formula (I) is added into the negative plate, so that the cycle performance of the battery can be improved.
The results of low-temperature discharge performance of the batteries provided in examples 1 to 3 and comparative example 1 are shown in fig. 3, and the battery of example 1 has a capacity retention rate higher than 75% at-20 ℃; the capacity retention of the cell of example 2 was still higher than 70% at-20 ℃; the capacity retention of the cell of example 3 was still close to 65% at-20 ℃. The battery of comparative example 1 had a capacity retention rate of only about 60% at-20 ℃. Therefore, the polymer shown in the formula (I) is added into the negative plate in the embodiment of the invention, so that the rate performance of the battery at low temperature can be improved.
The results of the rate charging performance tests of the batteries provided in examples 1 to 3 and comparative example 1 are shown in fig. 4, and the battery of example 1 has a constant current charging ratio higher than 80% at 7C high rate charging; the battery of example 2 had a constant current charge ratio of approximately 75% at 7C high rate charge; the battery of example 3 had a constant current charging ratio of more than 70% at 7C high rate charging. And the battery of comparative example 1 had a constant current charging ratio of less than 70% at the time of 7C high rate charging. Therefore, in the embodiment of the invention, the polymer shown in the formula (I) is added into the negative plate, so that the quick charge performance and the rate capability of the battery can be improved.
In a comprehensive view, the dosage of the first monomer is approximately close to that of the second monomer, the core-shell structure of the polymer is more stable, the stability of the ingredients and the cathode coating is higher, the hydrophilic end can be exposed under the action of an organic solvent after liquid injection, an anion-cation pair is formed, the electronic conduction and the lithium ion conduction are accelerated, the cycle performance, the low-temperature discharge performance and the multiplying power charging performance of the lithium ion battery are improved, the polarization of the battery can be reduced, and the service life is prolonged.
Further, the capacity retention rate was still higher than 93% at 500 cycles of the batteries of examples 4 and 5, was still higher than 78% at-20 ℃ and the constant current charging rate was higher than 85% at 7C high rate charging. The addition of the halogen-containing hydrolyzable esters in the polymer is proved to accelerate the conduction speed of lithium ions and electrons and further improve the quick charge performance of the battery.
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element. Furthermore, it should be noted that the scope of the methods and apparatus in the embodiments of the present application is not limited to performing the functions in the order shown or discussed, but may also include performing the functions in a substantially simultaneous manner or in an opposite order depending on the functions involved, e.g., the described methods may be performed in an order different from that described, and various steps may also be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is to be construed as including any modifications, equivalents, and alternatives falling within the spirit and principles of the invention.

Claims (10)

1. A polymer, characterized in that the polymer is a block copolymer, comprising a repeating structural unit A shown in a formula (I) and a repeating structural unit B shown in a formula (II),
wherein R is 1 Comprises- (CH) 2 ) a NR 5 R 6 、-O(CH 2 ) a NR 5 R 6 、-CO(CH 2 ) a NR 5 R 6 、-COO(CH 2 ) a NR 5 R 6 ,R 5 And R is 6 Each independently selected from at least one of-H, -OH, C1-C12 alkyl or C6-C18 aryl, a is an integer from 0 to 10;
R 3 at least one of an alkyl group comprising C1-C12 or an acid ester thereof, or an aryl group comprising C6-C18 or an acid ester thereof;
R 2 and R is 4 Each independently comprisesH or C1-C3 alkyl.
2. The polymer of claim 1, wherein R 3 Comprising C1-C6 alkyl or acid ester thereof, or C6-C10 aryl or acid ester thereof, preferably R 3 Comprises at least one of methyl, ethyl, isopropyl, n-butyl, tolyl and sulfonic acid groups; preferably, the acid ester group is selected from the group consisting of-SO 3 - 、-P(OH) 3 、CrO 4 2- 、Cr 2 O 7 2- And NO 3- At least one of (a) and (b);
and/or R 5 、R 6 Each independently selected from-H, -OH, C1-C6 alkyl or C6-C12 aryl, preferably at least one selected from-H, -OH, methyl, ethyl, propyl, phenyl and tolyl;
and/or R 2 And R is 4 Each independently is H or methyl;
and/or, the content of the repeated structural unit A is 10-90wt% based on the total weight of the polymer, and the content of the repeated structural unit B is 10-90wt%; preferably, the content of the repeating structural unit A is 30 to 70wt% and the content of the repeating structural unit B is 30 to 70wt% based on the total weight of the polymer.
3. The polymer of claim 1, wherein the repeating structural unit a and the repeating structural unit B are connected by a C-C bond;
preferably, the polymer has a core-shell structure;
preferably, the repeating structural unit a is a shell and the repeating structural unit B is a core;
preferably, the number average molecular weight of the polymer is 10000g/mol to 50000g/mol.
4. The polymer of claim 1, wherein the repeating structural unit a comprises a first monomer having a structure of formula (ii), and the repeating structural unit B comprises a second monomer having a structure of formula (IV);
R 2 -CH=CH-R 1 formula (III),
wherein R is 1 Comprises- (CH) 2 ) a NR 5 R 6 、-O(CH 2 ) a NR 5 R 6 、-CO(CH 2 ) a NR 5 R 6 、-COO(CH 2 ) a NR 5 R 6 ,R 5 And R is 6 Each independently selected from at least one of-H, -OH, C1-C12 alkyl or C6-C18 aryl, a is an integer from 0 to 10;
R 2 at least one of an alkyl group comprising C1-C12 or an acid ester thereof, or an aryl group comprising C6-C18 or an acid ester thereof;
R 2 and R is 4 Each independently includes H or C1-C3 alkyl.
5. The polymer of claim 4, wherein the first monomer comprises N, N-dimethylaminoethyl methacrylate and/or N, N-dimethylacrylamide;
and/or the second monomer comprises one or more of methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, butyl methacrylate, benzyl methacrylate and sulfonate methacrylate.
6. The polymer according to any one of claims 1 to 5, wherein the polymer comprises a structure represented by the following formula (V):
wherein m is any integer from 100 to 10000, and n is any integer from 100 to 10000;
preferably, the molecules of the polymer comprise a structure represented by the following formula (IV):
wherein m is any integer from 100 to 10000, and n is any integer from 100 to 10000.
7. A negative electrode sheet comprising a negative electrode current collector and a negative electrode active material layer on one or both sides of the negative electrode current collector, the negative electrode active material layer comprising a negative electrode active material, a conductive agent, and the polymer of any one of claims 1 to 6.
8. The negative electrode sheet according to claim 7, wherein the negative electrode active material layer further comprises a halogen-containing ester;
preferably, the halogen-containing esters comprise ethyl chloroacetate and/or methyl chloroacetate.
9. The negative electrode sheet according to claim 7, wherein the weight content of the polymer is 0.5 to 3wt% based on the total weight of the negative electrode active material layer;
preferably, the mass ratio of the polymer to the halogen-containing ester is 1 (0.5-1.5).
10. A battery comprising the polymer of any one of claims 1-7 and/or the negative electrode sheet of claim 8 or 9.
CN202311857387.8A 2023-12-29 2023-12-29 Polymer, negative electrode plate and battery Pending CN117801186A (en)

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